1. Field of the Invention
The present invention relates to semiconductor nanoparticles and a fluorescent probe for biological labeling.
2. Description of the Related Art
A cell imaging technique is an important technique to investigate cell kinetics. Heretofore, cell imaging using various types of dyes has been developed, and in recent years, cell imaging using quantum dots which simultaneously have a high emission quantum yield, a high absorption coefficient, a wide absorption region, and a high durability has attracted attention. However, in imaging using quantum dots, particles containing cadmium (Cd), which may have some toxicity, are used in many cases, and hence development of high-brightness quantum dots using an alternative element having a low toxicity has been desired. In the circumstances as described above, for example, PTL 1 and NPLs 1, 2 have disclosed water-soluble semiconductor nanoparticles in which sulfo groups (—SO3H) are introduced in semiconductor nanoparticles formed of a ZnS—AgInS2 solid solution (ZAIS). Since nanoparticles become water soluble when sulfo groups are introduced therein and are hence likely to be incorporated into cells, the nanoparticles are expected to be used as quantum dots for cell imaging.